U.S. patent number 6,536,288 [Application Number 10/172,132] was granted by the patent office on 2003-03-25 for differential pressure sensor.
This patent grant is currently assigned to ABB Patent GmbH. Invention is credited to Dieter Binz, Peter Krippner, Wolfgang Scholz, Albrecht Vogel.
United States Patent |
6,536,288 |
Scholz , et al. |
March 25, 2003 |
Differential pressure sensor
Abstract
There is described a differential pressure sensor made using
glass-silicon technology with a diaphragm plate arranged between
two carrier plates. To achieve a high resolution at the beginning
of the measuring range in conjunction with high overload
resistance, the measuring diaphragm plate of the sensor has for a
prescribed measuring range within the same measuring chambers a
plurality of mutually independent deflectable regions as measuring
diaphragms. Each such region acts as a part-sensor with a
part-measuring range. The part-measuring ranges of the part-sensors
overlap and in total are equal to the prescribed measuring range of
the differential pressure sensor. The displacement of the measuring
diaphragm of each part-sensor is mechanically limited outside its
part-measuring range by the carrier plates.
Inventors: |
Scholz; Wolfgang (Minden,
DE), Vogel; Albrecht (Stutensee, DE),
Krippner; Peter (Karlsruhe, DE), Binz; Dieter
(Hirschberg, DE) |
Assignee: |
ABB Patent GmbH (Mannheim,
DE)
|
Family
ID: |
7689229 |
Appl.
No.: |
10/172,132 |
Filed: |
June 14, 2002 |
Foreign Application Priority Data
|
|
|
|
|
Jun 23, 2001 [DE] |
|
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101 30 372 |
|
Current U.S.
Class: |
73/718 |
Current CPC
Class: |
G01L
9/0073 (20130101) |
Current International
Class: |
G01L
9/00 (20060101); G01L 009/12 () |
Field of
Search: |
;73/718,724,715,716,722,723 ;361/283.1,283.2,283.3,283.4
;156/272.2,273.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Oen; William
Attorney, Agent or Firm: Rickin, Esq.; Michael M.
Claims
What is claimed is:
1. A capacitive differential pressure sensor comprising: a. two
glass carrier plates; and b. a diaphragm plate of silicon serving
as a first electrode and with a pressure-sensitively deflectable
region arranged between said two carrier plates; said diaphragm
plate and each carrier plate being integrally connected to one
another in their edge region by anodic bonding such that each of
said two carrier plates combine with said diaphragm plate to form a
measuring chamber, each of said carrier plates having a pressure
supply duct, which runs perpendicular to the contact surfaces of
said diaphragm plate and of said carrier plates and through which
the respective measuring chamber can be pressurized, the surfaces
of said carrier plates lying adjacent said deflectable region of
said diaphragm plate forming a first electrode and said surfaces of
said carrier plates lying opposite the deflectable region of the
diaphragm plate are each provided with a metallization, serving as
a second electrode, in such a way that the first electrode and the
second electrodes form a differential-pressure-dependent capacitor
arrangement said diaphragm plate having for a prescribed measuring
range within the same measuring chambers a plurality of mutually
independent deflectable regions as measuring diaphragms for in each
case a part-sensor with a part-measuring range, the overlapping of
all the part-measuring ranges of the part-sensors being equal to
the prescribed measuring range of the differential pressure sensor,
and the displacement of the measuring diaphragms of each
part-sensor is mechanically limited outside its part-measuring
range.
2. The differential pressure sensor of claim 1 wherein said
part-measuring ranges are formed by said part-sensors following one
another in said measuring range and overlapping one another at the
limits of said measuring range.
3. The differential pressure sensor of claim 1 wherein said
part-measuring ranges of said part-sensors are set by the rigidity
of said associated measuring diaphragms adapted to said
part-measuring range.
4. The differential pressure sensor of claim 1 wherein said
part-measuring ranges of said part-sensors are set by the rigidity
of said associated measuring diaphragms adapted to said
part-measuring range.
5. The differential pressure sensor as claimed in claim 3, wherein
the diaphragm thickness of the measuring diaphragm is the same for
all the part-sensors and the surface area of each measuring
diaphragm is set in dependence on the respective part-measuring
range.
6. The differential pressure sensor as claimed in claim 4, wherein
the diaphragm thickness of the measuring diaphragm is the same for
all the part-sensors and the surface area of each measuring
diaphragm is set in dependence on the respective part-measuring
range.
7. The differential pressure sensor as claimed in claim 3, wherein
the diaphragm thickness and the surface area of the measuring
diaphragm are the same for all the part-sensors and each measuring
diaphragm has reinforcing structures, in dependence on the
respective part-measuring range.
8. The differential pressure sensor as claimed in claim 4, wherein
the diaphragm thickness and the surface area of the measuring
diaphragm are the same for all the part-sensors and each measuring
diaphragm has reinforcing structures, in dependence on the
respective part-measuring range.
9. The differential pressure sensor as claimed in one of claim 1,
wherein the part-sensor with the highest part-measuring range is
duplicated.
10. The differential pressure sensor as claimed in one of claim 2,
wherein the part-sensor with the highest part-measuring range is
duplicated.
11. The differential pressure sensor as claimed in one of claim 3,
wherein the part-sensor with the highest part-measuring range is
duplicated.
12. The differential pressure sensor as claimed in one of claim 4,
wherein the part-sensor with the highest part-measuring range is
duplicated.
13. The differential pressure sensor as claimed in one of claim 1,
wherein the measuring chambers are divided into sectors which are
hydropneumatically connected to one another, a part-sensor being
arranged in each pair of sectors.
14. The differential pressure sensor as claimed in one of claim 12
wherein the measuring chambers are divided into sectors which are
hydropneumatically connected to one another, a part-sensor being
arranged in each pair of sectors.
15. The differential pressure sensor as claimed in one of claim 3,
wherein the measuring chambers are divided into sectors which are
hydropneumatically connected to one another, a part-sensor being
arranged in each pair of sectors.
16. The differential pressure sensor as claimed in one of claim 4,
wherein the measuring chambers are divided into sectors which are
hydropneumatically connected to one another, a part-sensor being
arranged in each pair of sectors.
17. The differential pressure sensor as claimed in claim 13,
wherein the sectors of a measuring chamber are hydropneumatically
connected to one another in a star-shaped manner, starting from the
pressure supply duct.
18. The differential pressure sensor as claimed in claim 14,
wherein the sectors of a measuring chamber are hydropneumatically
connected to one another in a star-shaped manner, starting from the
pressure supply duct.
19. The differential pressure sensor as claimed in claim 15,
wherein the sectors of a measuring chamber are hydropneumatically
connected to one another in a star-shaped manner, starting from the
pressure supply duct.
20. The differential pressure sensor as claimed in claim 16,
wherein the sectors of a measuring chamber are hydropneumatically
connected to one another in a star-shaped manner, starting from the
pressure supply duct.
21. The differential pressure sensor as claimed in claim 13,
wherein the sectors of a measuring chamber are hydropneumatically
connected to one another in a ring-shaped manner with the inclusion
of the pressure supply duct.
22. The differential pressure sensor as claimed in claim 14,
wherein the sectors of a measuring chamber are hydropneumatically
connected to one another in a ring-shaped manner with the inclusion
of the pressure supply duct.
23. The differential pressure sensor as claimed in claim 15,
wherein the sectors of a measuring chamber are hydropneumatically
connected to one another in a ring-shaped manner with the inclusion
of the pressure supply duct.
24. The differential pressure sensor as claimed in claim 16,
wherein the sectors of a measuring chamber are hydropneumatically
connected to one another in a ring-shaped manner with the inclusion
of the pressure supply duct.
25. The differential pressure as claimed in claim 1, wherein said
sensor is embedded in a pressure-resistant casing of ceramic
injection-molded material.
26. The differential pressure as claimed in claim 2, wherein said
sensor is embedded in a pressure-resistant casing of ceramic
injection-molded material.
27. The differential pressure as claimed in claim 3, wherein said
sensor is embedded in a pressure-resistant casing of ceramic
injection-molded material.
28. The differential pressure as claimed in claim 4, wherein said
sensor is embedded in a pressure-resistant casing of ceramic
injection-molded material.
Description
FIELD OF THE INVENTION
The invention relates to a differential pressure sensor made using
glass-silicon technology with a high overload resistance for
industrial applications.
DESCRIPTION OF THE PRIOR ART
For measuring differential pressures, usually piezoresistive or
capacitive pressure sensors are used. A common characteristic of
both is that a diaphragm is deformed pressure-dependently. The
degree of deformation is in this case a measure of the
pressure.
Piezoresistive pressure sensors are distinguished by high long-term
stability, a wide operating temperature range and a large measuring
range in conjunction with low temperature dependence and high
measurement dynamics. However, particularly in the case of high
pressures or differential pressures, piezoresistive pressure
sensors have an unsatisfactory resistance to overloading.
DE 200 19 067 discloses a pressure-measuring device with a
piezoresistive pressure sensor and hydraulic force transmission in
which the process pressure of the measuring medium is transmitted
to the pressure sensor by interposing a separating diaphragm with a
fluid diaphragm seal, the process-pressure-dependent,
diaphragm-seal-displacing deflection of the separating diaphragm
being mechanically limited to an amount prescribably exceeding the
measuring range, and the pressure sensor being arranged in the
pressure-measuring device in such a way that it can move on a
mechanically pretensioned overload diaphragm which, in dependence
on process pressure exceeding the measuring range, limits a
volumetrically variable equalizing space for accepting excess
diaphragm seal.
This construction is complex and also characterized by a large
number of joining processes between components subjected to
pressure, which place extreme demands on the joint, in particular
in the case of high limit pressures. Industrial applications of
differential pressure sensors require overload resistance up to 400
bar.
DE 42 07 949 discloses a capacitive differential pressure sensor
made using glass-silicon technology in which a plate of silicon,
serving as a pressure-sensitive diaphragm and as a first electrode,
is arranged between two carrier plates consisting of glass, the
plate and the carrier plate being integrally connected to one
another in their edge region by anodic bonding in such a way that
in each case a carrier plate combines with the plate serving as the
diaphragm to form a measuring chamber, each carrier plate has a
pressure supply duct, which runs perpendicular to the contact
surfaces of the plate and of the carrier plates and via which the
respective measuring chamber can be pressurized, and the surfaces
of the carrier plates lying opposite the deflectable region of the
plate serving as the diaphragm are each provided with a
metallization, serving as a second electrode, in such a way that
the first electrode and the second electrodes form a
differential-pressure-dependent capacitor arrangement.
The differential-pressure-dependent deformation of the plate
serving as a diaphragm brings about a change in capacitance of the
capacitor arrangement, the change in capacitance being a direct
measure of the differential pressure. The change in capacitance is
measured electrically. To allow a wide measuring range to be
covered with adequate measuring accuracy, it is necessary for the
deflectable region of the plate serving as a diaphragm to have a
displacement which is at odds with designing the differential
pressure sensor to be resistant to overloading. Industrial
applications of differential pressure sensors demand overload
resistance up to 400 bar.
In contrast thereto the differential pressure sensor of the present
invention has high overload resistance in conjunction with high
resolution at the beginning of the measuring range.
SUMMARY OF THE INVENTION
The invention proceeds from a known capacitive differential
pressure sensor made using glass-silicon technology, in which a
diaphragm plate of silicon, serving as a first electrode and with a
pressure-sensitively deflectable region, is arranged between two
carrier plates consisting of glass, the diaphragm plate and each
carrier plate being integrally connected to one another in their
edge region by anodic bonding in such a way that in each case a
carrier plate combines with the diaphragm plate to form a measuring
chamber, each carrier plate has a pressure supply duct, which runs
perpendicular to the contact surfaces of the diaphragm plate and of
the carrier plates and via which the respective measuring chamber
can be pressurized, and the surfaces of the carrier plates lying
opposite the deflectable region of the diaphragm plate are each
provided with a metallization, serving as a second electrode, in
such a way that the first electrode and the second electrodes form
a differential-pressure-dependent capacitor arrangement.
The essence of the invention consists in that the diaphragm plate
has for a prescribed measuring range within the same measuring
chambers a plurality of mutually independent deflectable regions as
measuring diaphragms for in each case a part-sensor with a
part-measuring range, the overlapping of all the part-measuring
ranges of the part-sensors being equal to the prescribed measuring
range of the differential pressure sensor, the displacement of the
measuring diaphragm of each part-sensor being mechanically limited
outside its part-measuring range.
The measuring range of the differential pressure sensor is made up
of the part-measuring ranges of the individual part-sensors. In
this case, the high resolution in the part-measuring range of each
part-sensor contributes to the resolution of the differential
pressure sensor over the entire measuring range. In a corresponding
way, the resolution at the beginning of the measuring range of the
differential pressure sensor is determined by the resolution of the
part-sensor with the part-measuring range for lowest differential
pressures. The number of part-sensors is governed by the width of
the measuring range of the differential pressure sensor and
required resolution over the measuring range. With an increasing
number of part-sensors, the measuring range of the differential
pressure sensor is increased while the resolution remains the same
and, within a prescribed measuring range of the differential
pressure sensor, the resolution is increased.
Consequently and advantageously, a single differential pressure
sensor is sufficient for a large number of different industrial
applications. As a result, the expenditure in production and
stockkeeping is reduced as a result of a smaller number of
different individual parts and higher unit numbers of the single
differential pressure sensor, this also being the case in
service.
If the applied differential pressure exceeds the measuring range of
a part-sensor by a prescribable amount, the measuring diaphragm of
this part-sensor comes to bear against the nearest carrier plate.
Consequently, the measuring diaphragm of this part-sensor is
effectively protected from being damaged by overload.
According to a further feature of the invention, the part-measuring
ranges are formed by part-sensors following one another in the
measuring range and overlapping one another at the measuring range
limits. In the measuring range limiting band produced as a result,
the differential pressure is measured by two part-sensors of
neighboring part-measuring ranges. It is obvious here that the two
part-sensors must produce the same measured value for differential
pressures in the measuring range limiting band of successive
part-measuring ranges.
This partial redundancy advantageously achieves the effect of
confirming measured values of the part-sensors for differential
pressures in the measuring range limiting bands of successive
part-measuring ranges.
According to a further feature of the invention, the various
part-measuring ranges of the part-sensors are set by the rigidity
of the measuring diaphragm, adapted to the respective
part-measuring range. The dependence of the respective
part-measuring range on the rigidity of the measuring diaphragm
achieves the same maximum displacement for all the part-sensors of
the differential pressure sensor.
Consequently, for overload protection, the mechanical displacement
limitation for all the part-sensors of the differential pressure
sensor is advantageously situated identically in one plane.
According to a refining feature of the invention, the rigidity of
the measuring diaphragm is set by the diaphragm surface area. In
this case, the diaphragm thickness of the measuring diaphragm is
the same for all the part-sensors. With the same diaphragm
thickness, measuring diaphragms with a smaller diaphragm surface
area have a greater rigidity than measuring diaphragms with a
larger diaphragm surface area. The measuring diaphragms of the
part-sensors with part-measuring ranges designed for high
differential pressures have a greater rigidity than the measuring
diaphragms of the part-sensors with part-measuring ranges designed
for low differential pressures.
In this case, all the measuring diaphragms are advantageously able
to be formed during production by a single depth structuring
process. With a diaphragm plate of silicon, it is advantageous to
bring about the depth structuring by etching. In this case, the
etching depth is proportional to the etching duration. With the
same diaphragm thickness of the measuring diaphragm for all the
part-sensors, all the measuring diaphragms are structured in a
single etching process of the same duration for all the measuring
diaphragms.
According to an alternative refining feature of the invention, the
diaphragm thickness and the surface area of the measuring diaphragm
are the same for all the part-sensors and each measuring diaphragm
has reinforcing structures, in dependence on the respective
part-measuring range.
This advantageously succeeds in accommodating a large number of
part-sensors on a diaphragm plate of small surface area. This
feature is particularly advantageous in the case of differential
pressure sensors for a wide measuring range in conjunction with
high resolution over the entire measuring range.
DESCRIPTION OF THE DRAWING
FIG. 1 shows a basic presentation of a differential pressure sensor
of the present invention with a plurality of part sensors in a
first embodiment.
FIG. 2 shows a sectional representation along line 0--0 of FIG.
1.
FIG. 3 shows a basic presentation of a differential pressure sensor
of the present invention with a plurality of part sensors in a
second embodiment.
FIG. 4 shows a basic presentation of a differential pressure sensor
of the present invention with a plurality of part sensors in a
third embodiment.
FIG. 5 shows a representation of a detail of a measuring diaphragm
with reinforcing structures.
FIG. 6 shows a graphic representation of the measuring range of the
differential pressure sensor of the present invention and its part
sensors.
FIG. 7 shows the sensor of the present invention embedded in a
casing.
DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
In FIG. 1, the lateral construction of a differential pressure
sensor 1 with six part-sensors 11 to 16 is represented in principle
in a first embodiment. In FIG. 2, an enlarged sectional
representation along the sectional line 0--0 in FIG. 1 is shown.
Hereafter, reference is made simultaneously to FIGS. 1 and 2.
The differential pressure sensor 1 essentially comprises a
diaphragm plate 2 of silicon, which is arranged between two carrier
plates 3 and 4 consisting of glass, the diaphragm plate 2 and each
carrier plate 3 and 4 being integrally connected to one another in
their edge region by anodic bonding in such a way that in each case
a carrier plate 3 and 4 combines with the diaphragm plate 2 to form
a measuring chamber 30 and 40.
Each carrier plate 3, 4 has a central pressure supply duct 37, 47,
which runs perpendicular to the plane of the contact surfaces of
the diaphragm plate 2 and of the carrier plates 3, 4 and to which
in each case six radially aligned capillaries 5 are connected. Each
capillary 5 opens out into a sector 31 to 36 and 41 to 46. With
reference to the plane of the diaphragm plate 2, a sector 31 to 36
adjoining the carrier plate 3 and a sector 41 to 46 adjoining the
carrier plate 4 are respectively arranged congruently as a related
pair of sectors 31/41 to 36/46.
In a corresponding way, the measuring chamber 30 limited by the
carrier plate 3 is divided into six sectors 31 to 36 and six
capillaries 5, connected to the pressure supply duct 37. The
measuring chamber 40 limited by the carrier plate 4 is divided into
six sectors 41 to 46 and six capillaries 5, connected to the
pressure supply duct 47.
The diaphragm plate 2 is designed in the region of congruence of
each pair of sectors 31/41 to 36/46 as a pressure-sensitively
deflectable measuring diaphragm 21 to 26. A pair of sectors 31/41
to 36/46 and the associated measuring diaphragm 21 to 26
respectively form one of the six part-sensors 11 to 16.
The part-sensors 11 to 16 are distributed in a star-shaped manner
in the differential pressure sensor 1. Each part-sensor 11 to 16 is
assigned a total of four electrodes for sensing the
pressure-dependent deflection of its measuring diaphragm 21 to 26.
Represented in FIG. 2 for the part-sensors 12 and 14 are the
associated electrodes 121 to 124 and 141 to 144, which are formed
as thin metallization layers. For each part-sensor 12 and 14, one
of the electrodes 121 and 141 is respectively attached to the
carrier plate 3 and one of the electrodes 124 and 144 is
respectively attached to the carrier plate 4. The electrodes 122
and 142 are arranged on the side of the measuring diaphragms 22 and
24 facing the carrier plate 3 and the electrodes 123 and 143 are
arranged on the side of the measuring diaphragms 22 and 24 facing
the carrier plate 4.
The pairs of electrodes 121/122, 123/124 and 141/142 and 143/144
arranged in the same sector 32, 42, 34 and 44 respectively form a
capacitor, the capacitance ratio of the capacitors of the same
part-sensor 12 and 14 being a measure of the difference between the
pressures in the measuring chambers 30 and 40.
The capacitance ratios are evaluated separately by electronic means
for each part-sensor 11 to 16. The measured values of the
part-sensors 11 to 16 are checked for plausibility and combined to
form a measured value for the differential pressure sensor 1.
The distance between the pairs of electrodes 121/122, 123/124 and
141/142 and 143/144 respectively forming a capacitor limits the
differential-pressure-dependent displacement of the measuring
diaphragms 21 to 26. In this case, the distance is made so small
that still usable capacitance values of the capacitors are achieved
with electrode surface areas of less than 1/10 mm.sup.2.
As soon as the difference in pressure exceeds the part-measuring
range 101 to 106 of a part-sensor 11 to 16 for a sustained period,
the adequate deflection of the associated measuring diaphragm 21 to
26 leads to the effect that, in the measuring chamber 30 or 40 of
low pressure, the electrodes touch, initially at points and, as the
difference in pressure increases, over their surface area. The
small distance between the pairs of electrodes 121/122, 123/124 and
141/142 and 143/144 respectively forming a capacitor provides
damage-free overload protection for each part-sensor 11 to 16.
The part-measuring ranges 101 to 106 of the part-sensors 11 to 16
are set by an adapted rigidity of the measuring diaphragms 21 to
26.
In the first embodiment, it is provided that the diaphragm
thickness of the measuring diaphragms 21 to 26 is the same for all
the part-sensors 11 to 16. With the same diaphragm thickness,
measuring diaphragms 21, 22 and 23 with a smaller diaphragm surface
area have a greater rigidity than measuring diaphragms 24, 25 and
26 with a larger diaphragm surface area. The measuring diaphragms
21, 22 and 23 of the part-sensors 11, 12 and 13 with part-measuring
ranges 101, 102 and 103 designed for high differential pressures
have a greater rigidity than the measuring diaphragms 24, 25 and 26
of the part-sensors 14, 15 and 16 with part-measuring ranges 104,
105 and 106 designed for low differential pressures.
In this case, all the measuring diaphragms 21 to 26 are
advantageously able to be formed during production by a single
depth structuring process. With a diaphragm plate 2 of silicon, it
is advantageous to bring about the depth structuring by etching. In
this case, the etching depth is proportional to the etching
duration. The etching depth is limited by a resist layer. This
resist layer expediently consists of silicon oxide. With the same
diaphragm thickness of the measuring diaphragms 21 to 26 for all
the part-sensors 11 to 16, all the measuring diaphragms 21 to 26
are structured in a single etching process of the same duration for
all the measuring diaphragms 21 to 26.
The differential pressure sensor 1 is embedded as is shown in FIG.
7 in a pressure-resistant casing 6 of ceramic injection-molded
material. The casing 6 encloses the differential pressure sensor 1
in one piece and comprises connection pieces 71, 72 for connecting
the measuring mechanism to process-pressure lines. This
advantageously avoids pressure-loaded joints in the measuring
mechanism.
Using the same reference numerals for the same means, a second
embodiment of the invention is represented in FIG. 3. The
differential pressure sensor 1 has six part-sensors 11 to 16, which
are distributed in a circular manner in the differential pressure
sensor 1, and a pressure supply duct 37 and 47 for each measuring
chamber. Each part-sensor 11 to 16 is designed in the region of
congruence of each pair of sectors 31/41 to 36/46 with a
pressure-sensitively deflectable measuring diaphragm 21 to 26.
The pressure supply ducts 37 and 47 are eccentrically arranged and
connected to the pairs of sectors 31/41 to 36/46 in each case via a
capillary 5 designed as a ring line.
In a corresponding way, the measuring chamber 30 limited by the
carrier plate 3 is divided into six sectors 31 to 36 and an annular
capillary 5, connected to the pressure supply duct 37. The
measuring chamber 40 limited by the carrier plate 4 is divided into
six sectors 41 to 46 and an annular capillary 5, connected to the
pressure supply duct 47.
The diaphragm thickness of the measuring diaphragms 21 to 26 is the
same for all the part-sensors 11 to 16. With the same diaphragm
thickness, measuring diaphragms 21, 22 and 23 with a smaller
diaphragm surface area have a greater rigidity than measuring
diaphragms 24, 25 and 26 with a larger diaphragm surface area. The
measuring diaphragms 21, 22 and 23 of the part-sensors 11, 12 and
13 with part-measuring ranges 101, 102 and 103 designed for high
differential pressures have a greater rigidity than the measuring
diaphragms 24, 25 and 26 of the part-sensors 14, 15 and 16 with
part-measuring ranges 104, 105 and 106 designed for low
differential pressures.
Using the same reference numerals for the same means, a third
embodiment of the invention is represented in FIG. 4. The
differential pressure sensor 1 has six part-sensors 11 to 16, which
are distributed in a circular manner in the differential pressure
sensor 1, and a centrally arranged pressure supply duct 37 and 47
for each measuring chamber, to which duct six radially aligned
capillaries 5 are respectively connected. Each capillary 5 opens
out into a sector 31 to 36 and 41 to 46. Each part-sensor 11 to 16
is designed in the region of congruence of each pair of sectors
31/41 to 36/46 with a pressure-sensitively deflectable measuring
diaphragm 21 to 26.
In this case, the diaphragm thickness and the surface area of the
measuring diaphragm 21 to 26 are the same for all the part-sensors
11 to 16 and each measuring diaphragm 21 to 26 has reinforcing
structures 20, in dependence on the respective part-measuring range
101 to 106, which are shown enlarged in FIG. 5 for the measuring
diaphragm 22.
Starting from a prescribed material thickness of the diaphragm
plate 2, the measuring diaphragms 21 to 26 are of lesser material
thickness than the diaphragm plate 2 as a result of material
removal. The reinforcing structures 20 are formed by partial
material removal over the surface area of the measuring diaphragm
22. To be precise, a reinforcing structure 20 is formed by a
central body of a greater material thickness arranged centrally in
relation to the measuring diaphragm 22. The greater the proportion
of the surface area of the measuring diaphragm 22 that is occupied
by the central body, the greater the rigidity of the measuring
diaphragm 22.
In addition, reinforcing structures 20 may be provided in the form
of radial webs. The rigidity of the measuring diaphragm 22
increases with increasing height and width of the webs.
For measuring diaphragms 21, 22 and 23 of the part-sensors 11, 12
and 13 with part-measuring ranges designed for high differential
pressures it is advantageous to form the reinforcing structures 20
in the form of a combination of a central body and radial webs.
Each part-sensor 11 to 16 is designed for measurement in a
part-measuring range 101 to 106. In FIG. 6, the part-measuring
ranges 101 to 106 of the part-sensors 11 to 16 and the measuring
range 10 of the differential pressure sensor 1 are graphically
represented. The overlapping of all the part-measuring ranges 101
to 106 produces the measuring range 10 of the differential pressure
sensor 1. In this case, the part-measuring ranges 101 to 106 are
formed by part-sensors 11 to 16 following one another in the
measuring range and overlapping one another at the measuring range
limits. In the measuring range limiting band produced as a result,
the differential pressure is measured by two part-sensors 11/12 to
15/16 of neighboring part-measuring ranges 101/102 to 105/106. It
is obvious here that the two part-sensors 11/12 to 15/16 must
produce the same measured value for differential pressures in the
measuring range limiting band of successive part-measuring ranges
101/102 to 105/106.
To validate measured values, it may be expedient to cover the
part-measuring range 106 of the part-sensor 16 for lowest
differential pressures completely by the next-higher part-measuring
range 105 of the part-sensor 15. In addition, it may be expedient
to duplicate the part-sensor 11 with the part-measuring range 101
for highest differential pressures.
It is to be understood that the description of the preferred
embodiment(s) is (are) intended to be only illustrative, rather
than exhaustive, of the present invention. Those of ordinary skill
will be able to make certain additions, deletions, and/or
modifications to the embodiment(s) of the disclosed subject matter
without departing from the spirit of the invention or its scope, as
defined by the appended claims.
* * * * *